Pooled Analysis Indicates That Low but Not High BMI Is Associated With Poorer Outcome in Metastatic Colorectal Cancer
In a study reported in the Journal of Clinical Oncology, Renfro et al found that low but not high body mass index (BMI) was associated with poorer progression-free and overall survival in patients receiving first-line treatment for metastatic colorectal cancer.
The analysis included individual data from 21,149 patients enrolled in 25 first-line metastatic colorectal cancer trials during 1997 to 2012 from the ARCAD (Aide et Recherche en Cancérologie Digestive) database.
Effect of BMI
BMI was prognostic for overall survival (P < .001) and progression-free survival (P < .001), with the risk curve having an L-shaped pattern—ie, risk was highest for patients with the lowest BMI, decreased until BMI of approximately 28 kg/m2, and remained similar for patients with higher BMI. The effect of BMI was significantly nonlinear on a log relative hazard scale for both overall survival (P < .001) and progression-free survival (P < .001).
Compared with obese patients, those with BMI of 18.5 kg/m2 had a 50% increased risk of death (95% confidence interval [CI] = 43%–56%) and a 27% increased risk of progression or death (95% CI = 20%–34%). The data suggested an increased risk in patients with BMI < 18.5 kg/m2.
BMI remained a significant prognostic indicator for both overall survival (P < .001) and progression-free survival P < .001) after adjustment for age, sex, performance status, colon vs rectal cancer, number of metastatic sites, previous chemotherapy, and presence vs absence of liver, lung, and lymph node metastases. Low BMI was associated with poorer overall survival for men vs women, and high BMI was associated with improved overall survival for men vs women (P < .001 for interaction); a similar relationship was not observed for progression-free survival. BMI was not predictive of treatment effect.
The investigators concluded: “Low BMI is associated with an increased risk of progression and death among the patients enrolled on the [metastatic colorectal cancer] trials, with no increased risk for elevated BMI, in contrast to the adjuvant setting. Possible explanations include negative effects related to cancer cachexia in patients with low BMI, increased drug delivery or selection bias in patients with high BMI, and potential for an interaction between BMI and molecular signaling pathways.”
Lindsay A. Renfro, PhD, of Mayo Clinic, Rochester, is the corresponding author for the Journal of Clinical Oncology article.
Supported by the ARCAD Foundation. For full disclosures of the study authors, visit jco.ascopubs.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
